1. Field of the Invention
The present invention relates to a determination device and a determination method for determining the category of a determination target based on a plurality of feature values regarding the determination target.
2. Description of the Related Art
There have been known determination devices that automatically determine the condition of a road surface on the basis of a captured image of the road surface or determination devices that automatically determines the condition on a silicon wafer on the basis of a captured image of the silicon wafer. Such determination devices classify conditions of an object captured in an image into a plurality of categories and, based on feature values such as luminance or color saturation of the image, determine the category to which the object belongs so that the condition of the object is determined.
Typically, for example, in a feature space having a feature value such as a coordinate axis, a conventional determination device considers the distribution of teaching data of each category as a set of normal distribution (contaminated normal distribution), estimates a probability density function indicating the occurrence probability of the data of each category, and determines the category of the target data based on the probability density function (see Japanese Laid-open Patent Publication No. 2004-274431).
Alternatively, a conventional determination device decides, within a feature space, on representative data (prototype) representing the distribution of the teaching data of each category and, based on the distance between the prototype and the target data within the feature space, determines the category of the target data (see Japanese Laid-open Patent Publication No. 2006-12069).